Turbidity plumes in Tampa Bay, Florida, were monitored during ship-channel dredging operations from February 1977 to August 1978 to document plume appearance and water quality, evaluate plume influence on the characteristics of Tampa Bay water, and provide a basis for transferring the information to other areas having generally similar sediment, dredge, disposal, containment, and tide conditions.
Sediment composition varied from 85 percent sand and shell fragments to 60 percent silt and clay. Plumes originating from the operation of one hopper dredge and three cutterhead-pipeline dredges, including one of the largest in the world, were investigated. Disposal methods included beach nourishment, stationary submerged discharge, oscillating surface discharge, and creation of emergent dikes using turbidity barrier containment. Tidal currents ranged from slack water to flow velocities of 0.60 meter per second.
Plumes were monitored simultaneously by (1) oblique and vertical 35-millimeter aerial photography and (2) water-quality sampling for determination of water clarity and concentrations of nutrients, metals, pesticides, and industrial compounds. Forty-nine photographs depict plumes ranging in length from a few tens of meters to several kilometers having turbidity levels ranging from less than 10 to 200,000 nephelometric turbidity units.
